"""
字符串相关工具
"""
#字符串逆序
def str_reverse(s):
    return s[::-1]

#字符串切片
def substr(s,x,y):
    return s[x:y]

#测试
if __name__ == "__main__":
    print(str_reverse("abcde"))
    print(substr('abcde',1,3))
